This proposed study will determine the feasibility of using an array of microelectrodes for applying electrical energy to transfer DNA in vivo to living cells. The study will first assemble appropriate microelectrodes, computer based hardware, and custom software to create a device for applying electric fields in vivo. The device will then be tested by delivering plasmid DNA to muscle in a rat model and analyzing gene expression. Results will be compared to standard "macro" electrodes that are commonly in use for DNA delivery. If successful, this study will demonstrate the utility of microelectrodes for DNA delivery to cells/tissue using a device with a lower power that can precisely deliver DNA to a desired location. Success will also be a motivator for future investigations as the microelectrodes proposed in this study can be made flexible to confirm to tissue topography, small enough to be applied laproscopically or on a catheter type device, and as an implantable device for multiple dose delivery uses.